Many organs of the human body contain electrical conducting bundles which transmit electrical impulses to induce movement of the muscles of the organ. The electrical conducting bundles of the heart, for example, carry the electrical stimulus which induces rhythmic beating.
A heart attack can damage one or more portions of the electrical conducting bundles which stimulate heartbeats. The damaged or abnormal portion of the conducting bundle disturbs or interferes with the path of the electrical stimulus which induces the muscles of the heart to beat rhythmically. As a result of this disturbance of the electrical stimulus, the muscles of the heart can be induced to produce abnormal beating or arrhythmia which can be fatal.
Cardiac arrhythmia has been successfully treated with medication in some cases, but when that treatment is ineffective, open heart surgery is usually required. In an open heart surgical procedure, an attempt is made to remove the diseased or damaged electrical conducting bundles so that the electrical stimulus for the heart muscle can pass through unobstructed, healthy tissue. Often, a heart attack results in the damage of only a relatively small portion of the electrical conducting tissue, but a much larger area of tissue is removed during surgery. This is primarily due to the inability of current diagnostic techniques to precisely locate the diseased or damaged area of the heart. As a precaution, it has therefore been the practice for surgeons to remove more tissue than is really necessary in order to ensure that only healthy tissue remains.
Prior art apparatus and treatment methods have been proposed to improve current techniques of locating the damaged electrical conducting bundles of various organs, and to treat the damaged area without surgery. For example, a substantial effort has been made in the prior art to develop devices which are capable of more accurately diagnosing abnormalities in electrical field-producing organs, such as the heart, in which the apparatus senses the electrical field produced by the organ and emits signals for analysis by mapping instrumentation. Diagnostic apparatus of this general type are disclosed in U.S. Pat. Nos. 4,522,212; 4,559,951; 4,601,294; 4,341,221; 4,240,441; 4,172,451; 3,313,293; 4,369,794; 4,573,473; 4,692,148; 4,699,147; and, 4,690,152.
A great deal of research and development has also taken place to develop apparatus which avoid invasive surgical procedures such as open heart surgery. A number of apparatus have been designed which employ in vivo catheters or probes insertable through various blood vessels having lasers capable of destroying abnormalities associated with the heart or other organs such as arteriosclerotic plaque deposits and the like. Representative patents which disclose these types of devices include U.S. Pat. Nos. 4,685,458; 4,681,104; 4,672,961; 3,804,095; 4,461,283; 4,469,098; 4,207,874; 4,266,548; 4,336,809; 4,120,293; 3,659,613; 3,906,953; 4,072,147; and, 4,685,458.
One limitation of both the diagnostic devices and laser treatment devices disclosed in the patents listed above is that none incorporate both a sensing or diagnostic capability, and a laser treatment capability. The apparatus for diagnosing abnormalities in electrical field-producing organs have no means to treat the abnormality once it is discovered and located. On the other hand, the laser treatment devices disclosed in the patents listed above have no diagnostic capability. It is difficult to use one device to locate an abnormality in an organ, remove that device and then position a second, treatment device at the precise location of the damaged area of the organ identified by the diagnostic device.
This problem has been recognized in the apparatus disclosed, for example, in U.S. Pat. Nos. 4,576,177 and 4,587,972. Apparatus of this general type comprise an in vivo catheter having one optic fiber for transmitting laser irradiation and an ultrasonic transducer mounted at the tip of the catheter which transmits and receives ultrasonic signals. The catheter is inserted within a blood vessel, for example, and the ultrasonic transducer at the tip of the catheter is activated to transmit ultrasonic pulses through the catheter and against an obstruction such as arteriosclerotic plaque deposits. The ultrasonic echoes from the obstruction are received by the catheter and transmitted back to instrumentation located exteriorly of the patient which identifies or maps the obstruction. A laser beam is then transmitted through the optical fiber to destroy the obstruction while the catheter remains in place at the site of the obstruction.
Another type of apparatus found in the prior art having both a sensing and treatment capability is disclosed, for example, in U.S. Pat. Nos. 4,146,019; 4,207,874; and, 4,669,467. These patents generally disclose a catheter or probe having a pair of optical fibers for transmitting and receiving light to illuminate the obstruction. One of the optic fibers transmits laser light to the obstruction and the second optic fiber receives the reflected light which is transmitted back to a viewer. Once the obstruction is illuminated, the treatment laser is activated to destroy the obstruction.
While apparatus employing ultrasonic pulses or illumination are capable of permitting the attending physician to "view" an area of an organ or blood vessel, both provide relatively distorted maps or pictures of the affected area. This is because the ultrasonic pulses or laser light must pass through the fluids in the body cavity or vessel within which the catheter is inserted, both in moving to the affected area and in reflecting back from the affected area, and such fluids distort the image reproduced for viewing. In addition, such ultrasonic pulses or laser light are unable to penetrate, for example, the endocarcium and epicardium of the heart, which creates further distortion of the image of the underlying tissue. The applicability of such devices for the treatment of abnormalities other than the removal of arteriosclerotic plaque and the like is therefore limited.